Is it because we don't understand that obesity is linked with deadly heart disease, diabetes, stroke and some cancers? Or is it that we've tried to lose weight and failed so many times that we throw our hands in the air and say, "I guess I'm here for a good time, not a long time”?

Professor Timothy Gill, director of Sydney University's Boden Institute of Obesity, Nutrition, Exercise and Eating Disorders, told Coach that most Australians are aware that there is a health risk of obesity.

But many people don't realise that they personally have to take action.

"There is acceptance from the public that this is an important and serious issue – what I think the problem is, is that they haven't taken personal ownership of the problem," he told Coach.

Here's why so many Australians appear to be ignoring their burgeoning bellies.

Extreme images make us feel skinny

Most health articles you read about obesity are accompanied with the obligatory image of a bulging waistline walking the city streets or sitting on a park bench.

And it's that image of morbid obesity that most Australians have in their head when they think about obesity.

"They represent the extreme end of the problem – that's not what the majority of obese people in Australia are," Professor Gill says.

"The misperceptions in the public about who is obese and what is obese can lead to self-denial."

Being overweight is normalised

With the sheer number of overweight and obese people in the community, it's easy for our own waistlines to seem normal.

"If people in your social group all have a higher BMI and have a certain way of eating and drinking then it becomes normalised and you are more likely to eat and drink like that," Associate Professor Amanda Salis, Boden researcher, told Coach.

"The flipside, which is very encouraging, is that when people in your social network have a lower BMI and eating and drinking behaviours that promote a healthy weight and body, then that tends to have an impact as well."

We make plans to lose weight ‘one day’

With the sheer volume of readily available high-calorie foods on offer 24/7, there's no denying that weight loss takes a lot of commitment and organisation.

So it's little wonder that a lot of people put off weight loss attempts for a future date when they hope to have more time and energy to prepare healthy foods and get to the gym.

"I have concern that people think they will lose weight 'one of these days'," Associate Professor Salis says.

"The trouble is that it seems that the longer you put off losing extra weight, the more your body is likely to see that extra weight as being normal."

"It would have been easier when you first gained the weight because your body will try to help you lose the weight," Associate Professor Salis says.

"Sooner is always better than later."

Repeated weight loss attempts are uninspiring

Research shows it's very difficult for most people to maintain weight loss long term, and if you've lost weight and regained it multiple times you often just want to throw your hands up in the air and declare "I give up".

"The research is showing that you're better off trying to lose some weight and gaining it back than not trying to lose it at all," Associate Professor Salis says.

Even if the weight loss is short-lived, Associate Professor Salis says it will give your body a period of time where it is at reduced risk of dangerous obesity-related conditions.

"The weight creep is normal," she says.

"People always feel terrible when the weight comes back on but people should just acknowledge that they are a normal human being and this is what happens to human beings when we lose weight. Get back to it with another burst of something that was effective for you."

Doctors don't always know how to deal

Associate Professor Salis says that many frontline health professionals aren't adequately trained in how to bring up obesity in a supportive way and help patients seek appropriate treatment.

"Health professionals are more likely to take a blaming approach and say things like, 'You're obese, can't you see what you are doing to yourself?' but research has shown that these kinds of messages are counter-productive," Associate Professor Salis says.

"It makes the person feel shamed and not want to go back to that doctor."

The wider community needs to get involved

As much as individuals need to get real about whether they're overweight or obese, Professor Gill says governments and communities also play a vital role.

"We need acceptance not just from individuals but from governments and health professionals that this is something that is important and it's not your fault," he says.

"We need to create environments that are much more supportive of the behaviours that we are expecting people to undertake – we can't expect kids to drink less soft drink and eat less junk food if we are not prepared to do something about the way it is marketed and the way it is pervasive all over the community."

People think obesity is not that dangerous

Some obesity experts have argued that being overweight is not that dangerous and that statistics show that people with an “overweight” body mass index often live just long and healthy lives as healthy weight individuals.

But Associate Professor Salis says this doesn't tell the whole story.

"Recent research suggests it’s only a matter of time before obese people who are metabolically healthy start facing health issues.

“And whether or not a person with excess weight develops illness, sooner or later the mechanical effects of excess weight and the resultant gait abnormalities, combined with systemic inflammation, are likely to take their toll," she writes on The Conversation.

"Overweight adults are more than twice as likely to develop knee osteoarthritis, and the risk increases with weight. Carrying excess weight also contributes to escalating difficulties in performing everyday activities, such as walking, getting out of a chair and climbing stairs."